Antigenic and Substrate Preference Differences between Scorpion and Spider Dermonecrotic Toxins, a Comparative Investigation

Abstract

The Hemiscorpius lepturus scorpion and brown spider Loxosceles intermedia represent a public health problem in Asia and America, respectively. Although distinct, these organisms contain similar toxins responsible for the principal clinical signs of envenomation. To better understand the properties of these toxins, we designed a study to compare recombinant Heminecrolysin (rHNC) and rLiD1, the major phospholipase D toxins of scorpion and spider venom, respectively. Using a competitive ELISA and a hemolytic inhibition test, we come to spot a cross reaction between scorpion and spider venoms along with an epitopic similarity between rHNC and rLiD1 associated with neutralizing antibodies. Results show that the ability of the rHNC to hydrolyze lysophosphatidylcholine (LPC) is equivalent to that of rLiD1 to hydrolyze sphingomyelin and vice-versa. rHNC exclusively catalyze transphosphatidylation of LPC producing cyclic phosphatidic acid (cPA). The in-silico analysis of hydrogen bonds between LPC and toxins provides a possible explanation for the higher transphosphatidylase activity of rHNC. Interestingly, for the first time, we reveal that lysophosphatidic acid (LPA) can be a substrate for both enzymes using cellular and enzymatic assays. The finding of the usage of LPA as a substrate as well as the formation of cPA as an end product could shed more light on the molecular basis of Hemiscorpius lepturus envenomation as well as on loxoscelism.

Characterization of an Allosteric Pocket in Zika Virus NS2B-NS3 Protease

“…Electrostatic interactions were treated using the particle-mesh Ewald algorithm with a cut-off of 10 Å. System minimization and equilibration were performed using the same protocol described in our previous work. , Three independent production simulations of 500 ns each were performed in the NPT ensemble at a temperature of 310 K and pressure control of 1 atm, totaling 1.5 μs of simulation time. The Langevin thermostat with a collision frequency of 5 ps –1 was used for temperature control, and pressure coupling was performed using isotropic position scaling.…”

Brown Spider Venom Phospholipase-D Activity upon Different Lipid Substrates

“…The α-clade PLD toxins strongly prefer sphingomyelin as a substrate to LPC or PC [ 14 , 30 ]. This high selectivity for sphingomyelin indicates a possible role in membrane disruption [ 31 ].…”

Genome-wide identification, structural homology analysis, and evolutionary diversification of the phospholipase D gene family in the venom gland of three scorpion species

“…Consistent with our study, the GPI-PLD, PC-PLD, and Loxosceles PLDs, which share distant homologies, are grouped as non-HKD enzymes, and plant and mammalian PXPH-PLD enzymes are grouped as HKD PLDs [ 33 , 40 , 42 ]. Citing that Loxosceles PLD with SMase activity had been classified as lacking HKD enzymes [ 42 ], and considering previous research in which comparing the recombinant phospholipase D toxins from Hemiscorpius and Loxosceles venom, the equal ability of these two PLDs for hydrolyzing lysophosphatidylcholine (LPC) and sphingomyelin was shown [ 43 ], so the scorpion PLD1 beta enzymes can be considered structurally and functionally homologous with most of the PLDs from Loxosceles (this must be proven experimentally), while scorpion PLD2 alpha is estimated to have similar functions to several members of mammalian PLDs that bear a PX domain and are represented by a duplicated HKD motif. It has been explained that these members of mammalian PLDs, in addition to lipase activity, hydrolyze phosphodiester bonds through the HKD catalytic motif [ 42 ].…”